Abstract 9163: Head-to-head Comparison Between the Prognostic Role of Two Functional Tests in a Population of Elderly Patients with Chronic Heart Failure
Background The six-minute walk test (6MWT) and the cardio-pulmonary exercise testing (CPx ) provide a valid assessment of functional performance in patients ( pts ) with HF but in elderly pts a comparison on prognostic validity of the 2 techniques has not been yet performed.
Aims: We sought to compare the prognostic ability of the two functional tests in risk stratification of elderly CHF pts.
Methods: We prospectively followed-up 170 stable HF outpatients on optimized medical therapy by using a thorough clinical, laboratory and instrumental evaluation, including the 6MWT and the CPX . The composite end-point was death or hospitalizations for cardiovascular causes.
Results Mean age was 71±11 years, 28 % were female, 43% had ischemic heart disease, 18 % were in NYHA class III, 70% were on beta-blockers, 13% had an advanced diastolic disfunction, echocardiographic left ventricular ejection fraction ( LVEF ) was 44±13 %, mean BNP was 358±482 pg /ml . The mean distance covered during the 6MWT was 329±104 m. Peak workload was 71±11 watts, peak oxygen consumption (PVO2) was 13.2±4 ml/kg/min, the slope of the regression line relating ventilation to CO2 output, (VE/VCO2 slope) was 34±7 Exercise oscillatory breathing was found in 79 pts (46 %). During a median follow-up of 13 months, 18 patients died of cardiovascular causes and overall 51 met the combined end point of death or cardiovascular hospitalization. Distance walked correlated significantly to PVO2 (r=0.47, p<.0001). By Cox multivariable analysis, independent predictors of outcome were mean distance covered during the 6MWT (HR 0.996, CI 95% 0.992-0.999), LVEF (HR 0.962, CI 95% 0.938 - 0.985) and PVO2 (HR 0.883, CI 95% 0.790-0.987).
Conclusions: Among elderly CHF pts 6MWT is not only a simple and reliable first-line test for quantification of exercise intolerance but retains a prognostic value independent of CPX derived PVO2. This is a cornerstone in functional assessment because the 6MWT is widely diffused, safe and may be more feasible than CPX in a population of elderly HF pts.
- © 2011 by American Heart Association, Inc.